1. Field of the Invention
The invention relates to the field of data storage systems, and in particular, to test systems for media drives of data storage systems.
2. Statement of the Problem
One type of data storage system used for storing large amounts of data is a tape storage system. A typical tape storage system includes one or more tape drives and a tape library. The tape library includes one or more racks for storing tape cartridges, a robot mechanism for accessing tape cartridges stored on the tape cartridge racks, and a library control unit. The tape library may vary in size from storing a few tape cartridges to storing thousands of tape cartridges. Under control of the library control unit, the robot mechanism is operable to locate a particular tape cartridge on the tape cartridge racks, retrieve the tape cartridge from a tape cartridge rack, transport the tape cartridge to a tape drive, and insert the tape cartridge into the tape drive. The tape drive then reads or writes data to the magnetic tape of the tape cartridge. After use of the tape cartridge is finished, the robot mechanism is operable to remove the tape cartridge from the tape drive, transport the tape cartridge to the appropriate tape cartridge rack, and insert the tape cartridge into the tape cartridge rack.
Host computers access the tape storage system in order to read data from or write data to the tape storage system. The host computers generally communicate with a tape drive of the tape storage system. The tape drive includes a host/drive interface, such as a parallel Small Computer System Interface (SCSI) or a Fiber Channel Protocol SCSI (FCP-SCSI), for communicating with a host computer. The tape drive also includes an automation/drive interface (ADI) for communicating with the library control unit. The ADI communicates according to an automation-to-drive command (ADC) set or protocol that is transported over a transport protocol, such as RS422.
To access a selected file stored in the tape storage system, a host computer contains information from which it can map a particular file to the tape cartridge on which the file is stored. The host computer transmits a command to the tape drive through the host/drive interface. The tape drive then transmits the command to the library control unit through the automation/drive interface. The library control unit identifies the location of the tape cartridge in the tape library, and instructs the robot mechanism to retrieve the appropriate tape cartridge and mount the tape cartridge in the tape drive. The library control unit also transmits responses to the tape drive through the automation/drive interface. The tape drive transmits the responses to the host computer through the host/drive interface. With the tape cartridge loaded in the tape drive, the host computer may read from or write to the desired file.
To determine whether the tape drives will work properly within a tape storage system, the tape drives are tested and their operation is evaluated. For instance, tape drives may be evaluated to determine whether they conform to specifications of a standards body. The tape drives may also be evaluated to determine whether they conform to specifications of a tape library of a particular customer or supplier. A tape drive under test is connected to a tape library. When connected to the tape library, human operators transmit test commands to the tape drive through a host computer. Responsive to the test commands, the tape drive communicates with the library control unit and/or the host computer, and the operation of the tape drive is evaluated. A problem with the current methods of testing tape drives is that the tape drives have to be connected to an actual tape library to be tested. The tape libraries are expensive and inflexible in their operation. It is difficult to cause tape libraries to perform unexpected behaviors that need to be handled by the tape drive and the rest of the system. Because different types of libraries may behave differently to the same stimulus, tape drives are tested with each different type of tape library into which the tape drive may be installed. Thus, the process of testing tape drives can be inefficient and expensive.